Rolling bearing, notably large-diameter rolling bearing

ABSTRACT

A rolling bearing provides an inner ring and an outer ring concentrically about a rotation axis X-X′ running in an axial direction, and at least first and second axial bearings each axially disposed between the inner ring and the outer ring and each having at least one row of rolling elements, the first and second axial bearings being spaced apart from each other in the axial direction. The rolling bearing further provides only one radial bearing radially disposed between the inner ring and the outer ring and having at least one row of rolling elements. The radial bearing is disposed between an outer raceway located on the inner ring and an inner raceway located on the outer ring.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to German Patent Application no.102019206039.0, filed Apr. 26, 2019, the contents of which are fullyincorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to the field of rolling bearings forabsorbing axial and radial forces and having an inner ring and an outerring arranged concentrically about an axis of rotation running in anaxial direction.

The invention relates more particularly to the field of large-diameterrolling bearings, notably those used in a tunnel boring machine, or inthe field of defence such as radars, chars, or excavator applications.Large-diameter rolling bearings may also be used for the mounting ofrotor blades on wind turbines.

BACKGROUND OF THE INVENTION

A large-diameter rolling bearing comprises generally two concentricinner and outer rings, and a bearing assembly comprising two rows ofaxial rollers and one row of radial rollers. Such rolling bearings aregenerally loaded, both axially and radially, often with a relativelystrong load.

Depending on the use of roller bearing, considerable forces may arise,which may cause deformation of the bearing, notably of the rotatingring, leading in some cases, to locally separate the rings. As a matterof fact, a radial gap between rotating ring and fixed ring of the rollerbearing can be created.

In order to overcome this drawback, the rolling bearing disclosed inpatent EP2307745 B1 comprises a radial bearing radially disposed betweenthe inner and outer rings, and an axial roller bearing and a combinedradial-axial roller bearing that are axially disposed between the rings.

However, such rolling bearing is not able to bear high axial load andhigh tilting moment.

Reference can also be made to the roller bearing disclosed in patentEP2092204 B1 which was developed to realize a more uniform forcedistribution and counteract the deformation of the rings. This rollingbearing comprises two opposite radial bearings and two opposite axialbearings disposed in such a way to surround a nose ring of the outerring.

However, radial dimension of such rolling bearing requires aconsiderable installation space. Otherwise, the mounting of the fourbearings also requires a large number of assembly steps.

One aim of the present invention is to overcome these drawbacks.

SUMMARY OF THE INVENTION

It is a particular object of the present invention to provide a rollingbearing capable of absorbing axial and radial loads as well assupporting radial deformation which may occur under high radial loads.

In one embodiment, the rolling bearing comprises an inner ring and anouter ring which are arranged concentrically about a rotation axisrunning in an axial direction, and at least first and second axialbearings each axially disposed between the inner ring and the outerring, the first and second axial bearings being spaced apart from eachother in the axial direction. The first and second axial bearings eachhave at least one row of rolling elements.

The rolling bearing further comprises only one radial bearing radiallydisposed between the inner ring and the outer ring, and having at leastone row of rolling elements.

According to a general feature of the invention, the radial bearing isdisposed between an outer raceway located on the inner ring and an innerraceway located on the outer ring.

The terms “axial bearings” is understood to mean bearings adapted toaccommodate axial loads whereas the terms “radial bearing” is understoodto mean bearing adapted to accommodate radial loads.

With such an arrangement of the radial bearing, radial deformation ofthe rolling bearing and gap opening between inner ring and outer ring inradial direction are limited.

Besides, with the two axial bearings, the rolling bearing is able tobear high axial load and high tilting moment.

Otherwise, with regard to a rolling bearing comprising two radialbearings radially disposed between the inner and outer rings, the numberof parts used to form the rings is limited with the new design of therolling bearing. The installation space required is reduced and thedesign of the rolling bearing is compact.

The radial bearing may be radially offset with respect to the first andsecond axial bearings. Preferably, the radial bearing is axially locatedbetween the first and second axial bearings. Accordingly, the radialbearing does not project in the axial direction beyond the first andsecond axial bearings. Thanks to this arrangement, in the axialdirection, there is no additional space requirement for the arrangementof the radial bearing.

In one embodiment, one of the inner and outer rings comprises an annulargroove opening in a radial direction towards the other ring and intowhich a protruding nose of the other ring is located.

The first and second axial bearings can be disposed axially on each sideof the protruding nose of the other ring. The first and second axialbearings can be each axially disposed between the protruding nose of theother ring and the groove of the ring.

In a particular embodiment, the protruding nose of the other ring andthe ring each have a projection that respectively engage behind oneanother in the radial direction, the outer and inner raceways for theradial bearing being located on the projections. In particular, at leastthe projection of the other ring may have an L-shape with a radialportion and an axial portion. The axial portion may extend a free end ofthe radial portion.

In one embodiment, the ring comprising the groove is divided in theaxial direction in at least a support part and a holding part securedtogether, the outer or inner raceway for the radial bearing beinglocated on the support part. The first axial bearing may be axiallydisposed between the support part and the other ring. The second axialbearing may be axially disposed between the holding part and the otherring. The support part and the holding part of the ring may delimittogether the annular groove.

The ring of the rolling bearing may be the inner ring and the other ringmay be the outer ring. Alternatively, the ring may be the outer ring andthe other ring may be the inner ring.

The first and second axial bearings and the radial bearing each compriseat least one row of rolling elements, for example cylindrical rollers.Alternatively, the use of other type of rolling elements, for exampleballs, can also be considered. Preferably, the first and second axialbearings and the radial bearing each comprise only one row of rollingelements. Alternatively, at least one of the first and second axialbearings and the radial bearing may comprise at least two rows ofrolling elements.

In one embodiment, the rolling bearing comprises only the first andsecond axial bearings axially disposed between the inner ring and theouter ring.

The rolling elements of the axial and radial bearings can be arranged incages for example made of plastic, steel, etc. The cage may be segmentedor made in one part. Alternatively, the rolling bearing may comprise aplurality of spacers disposed circumferentially between the rollingelements.

The raceways located on the inner and outer rings for the axial andradial bearings may be formed directly on the rings. The raceways may behardened.

Alternatively, the raceways located on the inner and outer rings may beformed by separated parts secured to the rings.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention and its advantages will be better understood bystudying the detailed description of specific embodiments given by wayof non-limiting examples and illustrated by the appended drawings onwhich:

FIG. 1 is a partial cross-section of a rolling bearing according to afirst example of the invention, and

FIG. 2 is a partial cross-section of a rolling bearing according to asecond example of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The rolling bearing 10 as illustrated on FIG. 1 is a large-diameterrolling bearing comprising a first ring 12 and an second ring 14. In theillustrated example, the first ring 12 is the inner ring of the rollingbearing whereas the second ring 14 is the outer ring. The rollingbearing 10 may for example be used in a tunnel boring machine, a windturbine or any other applications using a large diameter rollingbearing.

The inner and outer rings 12, 14 are concentric and extend axially alongthe bearing rotation axis X-X′ which runs in an axial direction.

The rolling bearing 10 also comprises first and second axial bearings16, 18 arranged axially between the inner and outer rings 12, 14, and aradial bearing 20 arranged radially between the rings.

The inner ring 12 comprises an annular groove 22 opening in a radialdirection outwardly towards the outer ring 14. The inner ring 12comprises an outer cylindrical surface 12 a from which the groove 22 isformed. The inner ring 12 further comprises two opposite radial frontalsurfaces 12 b, 12 c which axially delimit the outer surface 12 a of thering.

The outer ring 14 comprises an annular protruding lobe or nose 24engaging into the annular groove 22 of the inner ring. The nose 24extends radially inwards.

The first and second axial bearings 16, 18 are arranged axially betweenthe nose 24 of the outer ring and the groove 22 of the inner ring. Theradial bearing 20 is arranged axially between the nose 24 of the outerring and the groove 22 of the inner ring.

The first and second axial bearings 16, 18 are spaced apart from eachother in the axial direction. The first and second axial bearings 16, 18are disposed on each side of the nose 24 of the outer ring. The rotationaxes of the axial bearings 16, 18 are parallel one relative to anotherand perpendicular to the rotation axis X-X′ of the roller bearing 10.

In the illustrated example, the axial bearing 16, 18 comprises a row ofaxial cylindrical rollers 16 a, 18 a having a rotation axis 16 b, 18 bperpendicular to the rotation axis X-X′ of the roller bearing 10. Theaxial rollers 16 a, 18 a roll on raceways located on the groove 22 ofthe inner ring and on the nose 24 of the outer ring.

A first flank 22 a of the groove and a first flank 24 a of the nose 24axially facing the first flank 22 a delimit the raceways for the axialrollers 16 a. A second flank 22 b of the groove and a second flank 24 bof the nose axially facing the second flank 22 b delimit the racewaysfor the axial rollers 18 a. The opposite first and second flanks 22 a,22 b delimit axially the groove 22 of the inner. Similarly, the oppositefirst and second flanks 24 a, 24 b here delimit axially the nose 24 ofthe outer ring. The first and second axial bearings 16, 18 come intocontact with the opposite flanks 24 a, 24 b of the protruding nose 24.

In the illustrated example, the axial length of the rollers 16 a of thefirst axial bearing is larger than the one of the rollers 18 a of thesecond axial bearing. Alternatively, the axial length of the rollers 16a may be smaller than, or may be equal to, the one of the rollers 18 a.

The nose 24 of the outer ring is provided with an annular projection 26extending inwards. The projection 26 has an L-shape. The projection 26comprises a radial portion 26 a extending radially inward from the nose24, and a free axial portion 26 b extending a small-diameter edge of theradial portion.

In the illustrated example, the outer ring 14 is made in one part.

Alternatively, the outer ring 14 may be divided in the axial directionin at least two separate parts secured together. In another variant, thenose 24 may be made separately from the main part of the outer ring. Inthe illustrated example, a toothing is provided on the outer ring 14.

The inner ring 12 is divided in the axial direction in two separateparts, a support part 28 and a holding part 30 which are securedtogether. The support part 28 and the holding part 30 axially bear oneagainst the other. In the illustrated example, passage holes 32 areprovided on the support and holding parts 28, 30 which permit thefastening of these two part by bolts.

The support part 28 and the holding part 30 of the inner ring delimittogether the groove 22. The first flank 22 a, which delimits on theinner ring 12 the raceway for the axial bearing 16, is located on thesupport part 28. The second flank 22 a delimiting on the inner ring 12the raceway for the axial bearing 18 is located on the holding part 30.

The support part 28 of the inner ring comprises an annular axialprojection 34 extending axially towards the holding part 30 whileremaining axially distant. The projection 34 axially faces the radialportion 26 a of the projection 26 of the outer ring. The projection 34radially surrounds the axial portion 26 b of the projection 26. Theprojection 34 and the axial portion 26 b of the projection 26 areengaged behind one another and spaced in the radial direction. Theradial portion 26 a of the projection 26 is axially disposed between thesupport part 28 and the holding part 30.

Between the projection 34 of the inner ring and the projection 26 of thenose 24 of the outer ring, there is arranged the radial bearing 20. Moreprecisely, the radial bearing 20 is arranged radially between theprojection 34 and the axial portion 26 b of the projection 26.

The projection 34 of the inner ring delimits an outer raceway 36 for theradial bearing 20. The axial portion 26 b of the projection 26 of theouter ring delimits an inner raceway 38 for the radial bearing. The boreof the projection 34 delimits the outer raceway 36. The outer surface ofthe axial portion 26 b of the projection delimits the inner raceway 38.The outer raceway 36 radially faces the inner raceway 38. The radialbearing 20 is radially disposed between the outer raceway 36 delimitedon the inner ring 12 and the inner raceway 38 delimited on the outerring 14.

The rotation axis of the radial bearing 20 is coaxial with the rotationaxis X-X′ of the roller bearing 10. In the illustrated example, theradial bearing 20 comprises a row of radial cylindrical rollers 20 ahaving a rotation axis 20 b parallel to the rotation axis X-X′. Theradial rollers 20 a roll on the outer and inner raceways 36, 38 locatedon the inner and outer rings.

The radial bearing 20 is radially offset inwards with respect to thefirst and second axial bearings 16, 18. The radial bearing 20 is axiallylocated between the first and second axial bearings 16, 18.

Otherwise, as previously mentioned, in this illustrated example, thefirst ring of the rolling bearing is the inner ring 12 whereas thesecond ring is the outer ring 14.

As an alternative, it could be possible to provide a reversedarrangement with the first ring forming the outer ring 12 and the secondring forming the inner ring 14 as shown on FIG. 2, in which identicalparts are given identical references. In this second example, the groove22 formed on the outer ring 12 opens radially inwards and the nose 24 ofthe inner ring extends radially outwards.

The axial portion 26 b of the projection 26 of the inner ring delimitsthe outer raceway 36 for the radial bearing 20. The projection 34 of theouter ring delimits the inner raceway 38 for the radial bearing 20. Moreprecisely, the bore of the axial portion 26 b of the projection delimitsthe outer raceway 36. The outer surface of the projection 34 delimitsthe inner raceway 38. In this embodiment, the outer raceway 36 for theradial bearing is still located on the inner ring 12, and the innerraceway 38 for the radial bearing is located on the outer ring 14. Theradial bearing 20 is radially offset outwards with respect to the firstand second axial bearings 16, 18.

1. A rolling bearing comprising: an inner ring and an outer ringarranged concentrically about a rotation axis running in an axialdirection, at least first and second axial bearings each axiallydisposed between the inner and outer rings and each having at least onerow of rolling elements, the first and second axial bearings beingspaced apart from each other in the axial direction, and a single radialbearing radially disposed between the inner and outer rings and havingat least one row of rolling elements, wherein the radial bearing isdisposed between an outer raceway located on the inner ring and an innerraceway located on the outer ring.
 2. The rolling bearing according toclaim 1, wherein the radial bearing is radially offset with respect tothe first and second axial bearings.
 3. The rolling bearing according toclaim 1, wherein the radial bearing is axially located between the firstand second axial bearings.
 4. The rolling bearing according to claim 1,wherein one of the inner and outer rings (12) comprises an annulargroove (22) opening in a radial direction towards the other ring (14)and into which a protruding nose (24) of the other ring (14) is located.5. The rolling bearing according to claim 4, wherein the first andsecond axial bearings (16, 18) are disposed axially on each side of theprotruding nose (24) of the other ring (14).
 6. The rolling bearingaccording to claim 4, wherein the first and second axial bearings (16,18) are each axially disposed between the protruding nose (24) of theother ring (14) and the groove (22) of the ring.
 7. The rolling bearingaccording to claims 4, wherein the protruding nose (24) of the otherring (14) and the ring (12) each have a projection (26, 34) thatrespectively engage behind one another in the radial direction, theouter and inner raceways (36, 38) for the radial bearing (20) beinglocated on the projections (26, 34).
 8. The rolling bearing according toclaim 7, wherein at least the projection of the other ring has anL-shape with a radial portion and an axial portion.
 9. The rollingbearing according to claim 4, wherein the ring (12) comprising thegroove (22) is divided in the axial direction in at least a support part(28) and a holding part (30) secured together, the outer or innerraceway (36, 38) for the radial bearing (20) being located on thesupport part (28), and wherein the first axial bearing (16) is axiallydisposed between the support part (28) and the other ring (14), thesecond axial bearing (18) being axially disposed between the holdingpart (30) and the other ring (14).
 10. The rolling bearing according toclaim 1, wherein the first and second axial bearings and the radialbearing each comprise only one row of cylindrical rollers.